The invention relates to a cooling device for cooling a catheter.
The invention further relates to a cryosurgery system.
Moreover, the invention further relates to a method of cooling a catheter.
Cryosurgery is the application of extreme cold to destroy abnormal or diseased tissue. Cryosurgery works by taking advantage of the destructive force of freezing temperatures on cells. At low temperatures, ice crystals may form inside the cells, which can tear them apart. More damage may occur when blood vessels supplying the tissue freeze.
In cryosurgery and cyroablation, precooling a refrigerant may enable a more efficient use of a refrigerant. Less refrigerant may be needed, and smaller dimensions are possible. More freezing cycles can be obtained from a given amount of refrigerant. Less-boiling may be achieved in a supply line of the refrigerant.
The pressure of the primary refrigerant may vary with the ambient temperature. Thus, often a pressure reduction is carried out for operating the catheter at a defined pressure. In US 2003/0149428A1 a method is described for simultaneous precooling of the primary refrigerant below its boiling temperature at the selected pressure. Simultaneous control of pressure and temperature is termed conditioning.
U.S. Pat. No. 6,471,694 discloses an apparatus for automatic operation of a refrigeration system to provide refrigeration power to a catheter for tissue ablation or mapping. The primary refrigeration system can be open loop or closed loop, and a precool loop is a closed loop. Equipment and procedures are disclosed for bringing the system to the desired operational state, for controlling the operation by controlling refrigerant flow rate, for performing safety checks, and for achieving safe shutdown.
Other methods of precooling a primary refrigerant in cryosurgery by the use of a secondary refrigerant are disclosed in U.S. Pat. No. 5,758,505, U.S. Pat. No. 6,237,355, U.S. Pat. No. 6,530,234, U.S. Pat. No. 7,004,936, WO 02/069820 A2 and GB 2,360,573 A.
Furthermore, alternatively to a secondary refrigerant, a Stirling engine or a Peltier element may be used for precooling as described in US 2003/0149428A1 and WO 02/13710 A1.